This invention relates to the art of compression tools for joining pipes and couplings and, more particularly, to improvements in connection with the pivotal jaw arm members for a compression tool.
Compression tools for joining tubes or pipes and coupling components are well known as shown, for example, in U.S. Pat. No. 6,035,775 to Nghiem and U.S. Pat. No. 6,434,998 to Amherd. Such tools include a compression jaw set removably mounted on a drive mechanism by which the jaw arms of the set are displaced into compression about a pipe and coupling to join the latter. The jaw set is comprised of a pair of jaw arm members pivotally mounted between a pair of side plates and having inwardly open, opposed jaw recesses at one end and laterally inwardly facing cam surfaces at the opposite ends. The jaw arms are pivotal about pins located in openings through the jaw arms between the opposite ends thereof, and the jaw set is mountable on the drive mechanism by means of the side plates and at a location relative to the jaw set which is laterally between the pivot pins and between the pivot pins and cam surfaces of the jaw members. The drive mechanism includes cam rollers which are displaceable axially forwardly and rearwardly along the cam surfaces of the jaw members and, when displaced forwardly of the cam surfaces, the rollers engage the latter and displace the opposed jaw recesses toward one another and constrictably about a pipe and coupling disposed therebetween.
The jaw recesses are of course contoured to compressibly engage a pipe and coupling therebetween so as to sealingly interengage the components without the use of solder. Accordingly, it is critical that the jaw recesses be aligned perpendicular to the axes of the pipe and coupling during the compression operation. Failure to properly align the jaw recesses with the pipe and coupling can result in crushed fitting, or improper crimping of the pipe and coupling which can lead to leakage when the line being installed is placed in use, such as for delivering liquid under pressure. Alignment is somewhat difficult to achieve under any circumstances in that the operator of the compression tool must support the latter with the jaws open, engage the jaws about a pipe and coupling, and then actuate the drive mechanism to complete the compression process. Therefore, as will be appreciated from the aforementioned patent to Nghiem, the size and weight of the drive mechanism and jaw assembly add to the difficulty in obtaining and maintaining proper alignment between the jaw recesses, pipe and coupling, and the alignment process is made more difficult if the component parts to be compressed are located above the operator's head and/or in areas that are difficult to gain access to.
One effort to overcome the foregoing problem is shown in German Utility Model Application G 93 14 054.1 wherein jaw recesses which are integral with the jaw arm members are at an angle of about five degrees relative thereto. While such a disposition of the recesses does enable an operator to make a crimp close to an object, such as a wall, it remains that the jaw recesses are rigid relative to one another and thus to the pipe and coupling to be crimped, whereby care must be taken by the operator to assure proper alignment between the jaws and the components to be compressed.
Another approach to resolving the alignment problem is shown in U.S. Pat. No. 6,477,757 to Viegener wherein the jaw arms of a jaw set are adapted to receive an auxiliary crimping jaw attachment which is pivotal relative to the jaw arms to achieve alignment between the working faces of the attachment and the pipe and coupling to be crimped when the jaw set is attached to the drive. The attachment comprises a pair of jaw arms pivotally connected to provide a crimping ring assembly in which the jaw arms include jaw recesses which are rigid relative to one another. While this design does provide articulation between the crimping jaws of the attachment and the jaw arms of the jaw set, the design requires two separate assemblies, namely a crimping ring assembly and an actuator jaw assembly. Moreover, use of the device requires mounting of the attachment about a pipe and coupling to be crimped and, then, connection of the attachment with the jaw arms of the jaw set. It will be appreciated, therefore, that the design is expensive to construct and that use thereof is cumbersome and time-consuming and, in many cases, may require two operators to achieve the mounting of the attachment and the connection thereof to the jaw arms of the jaw set.